The present invention relates in general to couplings in a drive system, and more particularly to a drive system coupling which provides for isolation of torsional vibration due to non-constant drive forces.
In many mechanical devices it is necessary to drive a plurality of components from a single drive source such as a motor. This may be readily accomplished by interconnecting the various components and the motor through a drive belt or chain arrangements. The drive belt or chain engages a drive shaft of the motor through a gear or pulley. Likewise, through similar gear or pulleys, the drive belt or chain engages appropriate driven shafts for each of the various plurality of components. In order to assure that the drive belt functions properly, it must engage the various gears or pulleys with sufficient forces to prevent slipping or jumping.
Due to the described arrangement, forces on the drive shafts act both in the torsional direction to cause rotation of the shaft and in the radial direction to assure engagement with the drive chain is maintained. While the drive motor is running, as well as when it starts and stops, the torsional force on the driven shaft may not be constant and, as such, may cause undue vibration to be transmitted to the driven shaft. This vibration is transmitted to the component associated with the driven shaft, and may adversely effect operation of such component.
It is well known to provide an isolation member in the drive system to prevent the transmission of such vibration to any particular driven component. Typically, the isolation member is a flexible coupling between the driven shaft and the gear or pulley with which the drive chain or belt is associated. Such flexible coupling may be a spring or resilient member, such as rubber for example, located radially between the driven shaft and the gear or pulley with which the drive chain or belt is associated. While such isolation members provide the desired isolation of undue vibration to the particular component, through the driven shaft, they have an adverse effect on the radial forces required to maintain drive engagement between the drive belt and the driven shafts. That is, the isolation members may flex in the radial direction to the extent that the drive belt is no longer effective to act on the gear or pulley. Moreover, the radial force may result in an eccentricity of the drive coupling between the gear or pulley and the respective driven shaft.